F pour the hot agar solution into each of the

Info icon This preview shows pages 53–55. Sign up to view the full content.

View Full Document Right Arrow Icon
f) Pour the hot agar solution into each of the crucibles at your lab station until you have about 7 – 8 mm of agar solution in each crucible. (Use tongs – palm up!) As the agar solutions cool, a gel should form. This will take 15 to 20 minutes (setting the crucibles and beaker on ice will accelerate gel formation). After the gel has formed, the salt bridges for the various experiments are ready. g) Dispense 50 mL of 0.05 M AgNO 3 into a clean and dry 100 mL beaker. This will be used as the titrant. h) Dispense into a clean and dry 100 x 50 mm crystallization dish 20.0 mL of halide solution containing different amounts of Cl - , Br - , and I - ions. Add 50 mL of H 2 O . Add a magnetic stirring bar. i) Place a Ag wire electrode (the electrode must have a single yellow band) in the halide solution and tape it to the crystallizing dish. The Ag electrode should extend into the halide solution approximately 3 mm. The solution height will increase during the titration; it is important that the halide solution not come in contact with the black insulation on the silver electrode during the titration. If you start the titration with only 3 mm of the electrode in the mixed halide solution, you should not have to adjust the silver electrode height during the titration. j) Dispense 5 mL of 0.050 M Cu(NO 3 ) 2 solution into a crucible containing 5-7 mm agar. Place the copper electrode (in a rubber stopper) in a clamp to suspend it above the crucible so that 3 – 4 mm of the electrode is in the 0.050 M Cu(NO 3 ) 2 solution. The copper electrode should not touch the agar. k) Turn on stirring to ensure mixing. Record in your notebook the initial cell potential (using the 2 V full-scale setting). Plan on 75 additions (of 0.500 mL of silver nitrate). l ) Use the fixed 0.500 mL pipettor to titrate the halide solution using 0.500 mL additions of AgNO 3 . Record the cell potential in your notebook after each addition, with each
Image of page 53

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Chemistry 132 Lab Manual Page 54 partner making sure you do not miss any recordings. m) Continue adding silver nitrate until you have reached 37.5 mL of silver nitrate, which should take you past the last equivalence point. Cleanup Return the silver electrode to a TA. Remove the crystallizing dish and pour the contents into the appropriate hazardous waste container. Place the pipette tip in the solid hazardous waste. Clean other equipment and rinse with deionized water. Wipe your lab bench with a damp paper towel. Organize your area to match the photograph of the equipment. Data analysis and Lab Report a) Determine the number of moles of Ag + ions corresponding to the amount of titrant dispensed, and calculate the derivative for each addition. b) Make graphs of the potential E versus volume of titrant dispensed and of the derivative versus volume. c) Determine the equivalence point for each halide, and from this information, d) Determine the concentration of each halide in the original solution.
Image of page 54
Image of page 55
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern